CIALDI, Alessandro. – Navigator and scholar of hydraulic and nautical sciences, papal naval officer, b. Civitavecchia 9 Apr. 1807, d. Rome 16 June 1882. In 1840, as captain commanding a small naval squadron, he became the first European to ascend the Nile for 1,164 km from its mouth. After inscribing the name of Gregory XVI on the temple of Isis on the island of Philae, he returned to Rome (28 Aug. 1841) bearing a valuable collection of archaeological, nautical and natural-history material, together with four large alabaster parallelepipeds donated by the Viceroy of Egypt to the Pope for the rebuilding of the basilica of St Paul Outside-the-Walls.
It was largely through Cialdi’s efforts that the modest but well-organised papal fleet was able, in 1848, to operate successfully in the Adriatic alongside other Italian forces against the Austrian navy, and in 1860 to bring timely supplies of arms and munitions to the fortress of Ancona, then on the point of being besieged. In 1867 he adroitly thwarted bold attempts by Garibaldi’s followers to raid and land along the coasts of Lazio and up the Tiber, such as the Cairoli expedition; nor, in 1870, did he and his sailors remain inactive as events moved swiftly to their climax.
From that point on, loyal to the Pope, he withdrew into private life to devote himself to his favourite studies. Among his achievements may be recalled the regulation of the courses of the Tiber and the Serechio; improvements and refinements to the ports of Livorno, Genoa, Pesaro, Civitavecchia, Fiumicino and Anzio; and his not inconsiderable contribution to the technical and financial backing of the cutting of the Suez Isthmus and the conduct of the works themselves, even as a member of the special papal commission. He also played a major part in the planning and full, rational illumination of the Tyrrhenian coasts and harbours of the Papal State.
Cialdi’s principal scientific merit lay in his discovery and definitive formulation of the hydrodynamic theory of wave motion and of shore currents, for which, on 18 March 1878, the Paris Academy of Sciences enrolled him among its members; he had already belonged to the Pontifical Academy of the New Lincei since 1847 and became its president in 1879, succeeding Angelo Secchi. At his death he left his rich and rare scientific library to the city of Civitavecchia, where he was buried in the cemetery with an epitaph composed by the historian of the papal navy, Alberto Guglielmotti.
Among Cialdi’s more than fifty works, the following deserve special mention:
Relation de deux voyages exécutés par la marine militaire des Etats Romains dans les années 1840–42, in Annales maritimes et coloniales (Paris 1843);
Sul Tevere, sulla linea più conveniente per la unione dei due mari e sulla marina mercantile dello Stato Pontificio (Rome 1847);
Sul moto ondoso del mare e sulle correnti di esso specialmente su quello litorali (ibid. 1843; 2nd greatly enlarged ed. 1846);
Port Said. A M. F. De Lesseps..., lettre du comm. A. C., etc. (ibid. 1868);
Nozioni preliminari per un trattato sulla costruzione dei porti sul Mediterraneo (ibid. 1874);
Illuminazione e segnalamento dei litorali e dei porti (ibid. 1878).